A Novel Device for Deep-Inspiration Breath Hold (DIBH): Results from a Single-Institution Phase 2 Clinical Trial for Patients with Left-Sided Breast Cancer

PurposeTo validate a novel device developed at our institution for deep inspiration breath hold (DIBH) within a phase 2 clinical trial for left-sided breast cancer and to evaluate the dosimetric benefits of its use.Methods and MaterialsThe device uses an external mechanical reference for guiding the patient to the desired breath level and gives acoustic and visual feedback to the patient and the radiation therapists, respectively. A phase 2 clinical trial was performed for its validation. The thoracic amplitude was used as a surrogate of the inspiration level. The stability, repeatability, reproducibility, and reliability of DIBH using the device were analyzed. The dosimetric parameters of the heart, the left anterior descending coronary artery, the ipsilateral lung, the contralateral breast, and the target coverage using free breathing and DIBH were compared.ResultsThirty-eight patients were included in the analysis. The maximum population value of stability and repeatability were 1.7 mm and 3.3 mm, respectively. The reproducibility mean value was 1.7 mm, and population systematic and random errors were 0.3 mm and 0.9 mm, respectively. The reliability was 98.9%. Statistically significant dose reductions were found for the heart, the left anterior descending coronary artery, and the ipsilateral lung dosimetric parameters in DIBH, without losing dose coverage to the planning target volumes.ConclusionsThe validation of the device within the phase 2 clinical trial demonstrates that it offers reliable, stable, repeatable, and reproducible breast cancer treatments in DIBH with its dosimetric benefits.     

Deep Inspiration Breath Hold Reduces the Mean Heart Dose in Left Breast Cancer Radiotherapy

BackgroundPatients with left breast cancer who undergo radiotherapy have a non-negligible risk of developing radiation-induced cardiovascular disease (CVD). Cardioprotection can be achieved through better treatment planning protocols and through respiratory gating techniques, including deep inspiration breath hold (DIBH). Several dosimetric studies have shown that DIBH reduces the cardiac dose, but clinical data confirming this effect is limited. The aim of the study was to compare the mean heart dose (MHD) in patients with left breast cancer who underwent radiotherapy at our institution as we transitioned from non-gated free-breathing (FB) radiotherapy to gated radiotherapy (FB-GRT), and finally to DIBH.Patients and methodsRetrospective study involving 2022 breast cancer patients who underwent radiotherapy at West Pomeranian Oncology Center in Szczecin from January 1, 2014 through December 31, 2017. We compared the MHD in these patients according to year of treatment and technique.ResultsOverall, the MHD for patients with left breast cancer in our cohort was 3.37 Gy. MHD values in the patients treated with DIBH were significantly lower than in patients treated with non-gated FB (2.1 vs. 3.48 Gy, p < 0.0001) and gated FB (3.28 Gy, p < 0.0001). The lowest MHD values over the four-year period were observed in 2017, when nearly 85% of left breast cancer patients were treated with DIBH. The proportion of patients exposed to high (> 4 Gy) MHD values decreased every year, from 40% in 2014 to 7.9% in 2017, while the percentage of patients receiving DIBH increased.ConclusionsCompared to free-breathing techniques (both gated and non-gated), DIBH reduces the mean radiation dose to the heart in patients with left breast cancer. These findings support the use of DIBH in patients with left breast cancer treated with radiotherapy.Key words: breast cancer, gated radiotherapy, deep inspiration breath hold, free breathing gated radiotherapy, mean heart dose     

深吸气屏气技术在左侧乳腺癌术后放疗中的应用（附41例）

目的:探讨深吸气屏气(deep inspiration breath hold，DIBH)技术在左侧乳腺癌术后放射治疗中的剂量学优势。方法:对澳门镜湖医院在2016年4月至2017年12月期间连续收治的41例左侧乳腺癌患者，接受术后放疗的资料进行总结，比较DIBH和自由呼吸（free breath，FB）两种呼吸模式下放疗的剂量学差异，包括靶区适形性（conformity index，CI）和均匀性（homogeneity index，HI）参数，肺、心脏、左侧冠状动脉前降支（LAD）以及右侧乳腺剂量比较。结果:DIBH和FB两种模式下心脏的平均剂量、左侧冠状动脉前降支平均剂量、左肺V20有显著性差别，分别是（4.92±1.93）Gy vs （6.53±2.30）Gy（P<0.001）、（18.71±9.00）Gy vs （27.21±8.81）Gy（P<0.001）、（23.42±6.67）% vs （28.03±8.68）%（P<0.001）。单纯全乳/胸壁放疗与全乳/胸壁+区域淋巴结放疗两组在DIBH模式下，左肺V20下降的百分比分别为16.53%和24.86%，差异有统计学意义（P<0.05）。DIBH和FB的靶区适形性和均匀性均无差异。结论:采用DIBH可以显著减少心脏、冠状动脉和肺等重要器官的照射。无论是单纯乳腺/胸壁放疗还是合并区域淋巴结放疗，采用DIBH技术均可以临床获益。     

Prone Positioning With Deep Inspiration Breath Hold for Left Breast Radiotherapy

BackgroundWith advances in treatment, outcomes for early-stage breast cancer are improving. We investigated the combination of prone position and deep inspiration breath hold to decrease cardiac doses for left-sided breast radiotherapy.Material and MethodsFifteen patients with left-sided breast cancer were enrolled on a single-institution prospective study. Each patient underwent 2 prone positioned computed tomography simulation scans utilizing free breathing and breath-hold. Separate treatment plans for each computed tomography simulation scan were created using tangential fields, and heart and left lung doses were compared between free breathing and breath-hold plans. The technique with the lower mean dose for the heart was used for treatment. All patients were treated with a hypofractionated regimen of 40 to 42 Gy in 15 to 16 fractions, followed by a lumpectomy cavity boost of 10 Gy in 5 fractions when indicated. Wilcoxon paired signed rank tests and paired t tests were performed for statistical analysis of dosimetric endpoints.ResultsThe median age of our patients was 58 years (range, 40-72 years). One patient was not able to tolerate prone positioning at simulation, leaving 14 patients with evaluable paired scans. The average mean heart dose with free breathing and with breath-hold was 0.93 Gy and 0.72 Gy, respectively (P = .0063). The average max heart dose with free breathing and with breath-hold was 15.70 Gy and 7.19 Gy, respectively (P = .001). The average mean left lung dose with free breathing and with breath-hold was 0.65 Gy and 0.88 Gy, respectively (P = .011).ConclusionsOur results indicate that breath-hold using the real-time position management system may provide additional cardiac dose reduction in patients receiving prone left-breast radiotherapy treated with tangential fields.     

Evaluating cardiac substructure radiation exposure in breast rotational intensity modulated radiation therapy: Effects of cancer laterality,fractionation and deep inspiration breath-hold

PurposeRotational intensity-modulated radiation therapy currently has a growing role in breast cancer radiation therapy, since this radiation technique reduces cardiac radiation exposure while homogeneously covering target volumes. This study aims to evaluate radiation exposure of cardiac substructures across a broad spectrum of breast cancer cases differing by cancer laterality, fractionation regimen and addition of deep-inspiration breath hold.Materials and methodsCardiac substructures were delineated following guidelines endorsed by the European Society for Radiotherapy and Oncology (ESTRO) for forty-four breast cancer patients having undergone conserving surgery and adjuvant rotational intensity-modulated radiation therapy. Target volumes consisted of the whole breast with a boost, axillary and internal mammary nodes. Patients were treated using free-breathing technique for left-sided or right-sided, normofractionated or hypofractionated helical tomotherapy or volumetric modulated arc therapy, or using deep-inspiration breath hold for left-sided normofractionated volumetric modulated arc therapy. Mean and maximum doses to cardiac substructures were retrieved. Correlations were performed between mean- and maximum radiation doses to cardiac substructures.ResultsLeft-sided and right-sided irradiations were associated with different cardiac substructure exposure patterns despite comparable mean heart dose: 7.21 Gy for left-sided normofractionated regimen, 6.28 Gy for right-sided normofractionated regimen. Deep-inspiration breath hold reduced mean doses to almost all cardiac substructures for left-sided irradiation, but did not decrease maximum doses to coronary arteries. Correlations between mean- and maximum doses to cardiac substructures were usually moderate, but stronger for right-sided irradiation.ConclusionDespite comparable mean heart dose, cardiac substructure radiation exposure patterns with rotational intensity-modulated radiation therapy strongly depend on the breast side, which could trigger clinically different long-term cardiotoxicity events. Deep-inspiration breath hold improves cardiac substructure dosimetry. Mean- and maximum heart dose could probably not be used as surrogate markers for precise cardiac substructure evaluation. In a near future, clinical practice and cardiotoxicity studies could possibly gain by considering cardiac substructure in a more systematic manner, possibly relying on cardiac autosegmentation algorithms.     

左侧乳腺癌放疗相关心脏毒性的危险因素分析

 放射治疗是乳腺癌的重要治疗手段,由于左乳与心脏位置毗邻,设计照射野时常不能完全避开心脏。乳腺癌放射治疗增加了患缺血性心脏病、心包炎和瓣膜病的风险。年轻、高体重指数（body mass index, BMI）、肿瘤位于中央象限和胸骨旁区域与心脏受到高剂量辐射有关。放疗心脏毒性与放疗技术有很大关系,对于左乳切除术后放疗,多野调强适形放疗（IMRT）能够平衡靶区覆盖和正常组织受量,而左乳保乳术后放疗,采用双弧度容积旋转调强（VMAT）较多野IMRT更具优势。相比全乳照射,加速部分乳腺照射能够显著降低心脏剂量;而对于需要照射区域淋巴结的患者,采用容积旋转调强或螺旋断层放疗在减少心脏受量方面则显示出优势。相比自由呼吸,深吸气屏气放疗能够显著减少心脏和冠状动脉左前降支剂量;尤其是对于胸壁+区域淋巴结（包括内如淋巴结）放疗的患者采用深吸气屏气（deep inspiration breath hold, DIBH）放疗获益更多,而对于保乳术后仍为大乳腺的患者,采用俯卧位能减少心脏毒性。另外,左乳放疗期间同步曲妥珠单抗靶向治疗、芳香化酶抑制剂（aromatase inhibitors, AI）会影响心脏事件的发生。基于上述因素,在给左侧乳腺癌患者制定放疗计划时,应结合患者年龄、BMI、原发肿瘤位置、体型、术后乳腺大小、是否需要区域淋巴结照射,根据现有放疗设备,给予最优的放疗方案,同时减少增加心脏毒性的同步治疗,从而最大程度减少治疗导致的心脏不良反应。     

Resource requirements and reduction in cardiac mortality from deep inspiration breath hold (DIBH) radiation therapy for left sided breast cancer patients: A prospective service development analysis

Introduction

Use of deep inspiration breath hold (DIBH) radiation therapy may reduce long-term cardiac mortality. The resource and time commitments associated with DIBH are impediments to its widespread adoption. We report the dosimetric benefits, workforce requirements, and potential reduction in cardiac mortality when DIBH is used for left-sided breast cancers.

The impact of semilateral decubitus position on the dose-volume parameters of the heart and lung for left sided breast cancer patients: A comparative dosimetric study

Purpose

When treating breast cancer with radiation therapy, the impact of treatment position on heart and lung dose-volume parameters (DVPs) is largely dependent on the maximal heart distance (MHD) and central lung distance (CLD). We evaluate how much heart and lung sparing can be achieved using the semilateral decubitus (SLD) position without and with breath hold compared with the standard supine position for left-sided breast cancer patients. A secondary aim was to investigate the impact of MHD and CLD on heart and lung DVPs.

Heart-Sparing Capability and Positional Reproducibility of Continuous Positive Airway Pressure in Left-Sided Breast Radiation Therapy

PurposeOur purpose was to investigate the interfraction and intrafraction reproducibility and practical applicability of continuous positive airway pressure (CPAP) for left breast volumetric modulated arc therapy (VMAT).Methods and MaterialsInterfraction reproducibility of the position of the heart was evaluated by measuring the heart-to-target distance on 20 planning computed tomography (CT) and 300 daily cone beam CT of 20 patients with left breast cancer treated with a 15-fraction VMAT. The dosimetric metrics of the whole heart and its substructures were compared between CPAP and free-breathing based VMAT plans. Intrafraction reproducibility was evaluated by measuring the motions of the breast target and diaphragm in 4-dimensional CT of 20 female patients with nonbreast cancer. Lastly, we analyzed the CPAP compliance data of 237 consecutive patients with left-sided breast cancer with and without internal mammary node irradiation (IMNI).ResultsThe heart position was reproducible as evidenced by an absolute average heart-to-target distance error of 2.0 ± 2.0 mm. Compared with free-breathing, CPAP significantly reduced the mean heart dose and the dose to the left ventricle and left anterior descending artery. The average intrafraction position variation of the breast target was 0.5 ± 0.5, 2.5 ± 2.0, and 1.8 ± 1.4 mm in the mediolateral, craniocaudal, and anteroposterior directions, respectively. CPAP was successfully applied in 221 patients (93%), with a mean heart dose of 1.6 ± 0.7 Gy (IMNI: 2.0 Gy and no IMNI: 1.1 Gy).ConclusionsCPAP has adequate heart-sparing capability and sufficient reproducibility in VMAT for left-sided breast cancer treatment, with a high compliance rate. Thus, CPAP is applicable in routine practice for left-sided breast cancer radiation therapy.     

Deep inspiration breath hold to reduce irradiated heart volume in breast cancer patients

PURPOSE: To evaluate the use of deep inspiration breath hold (DIBH) during tangential breast radiation therapy as a means of reducing irradiated cardiac volume. METHODS AND MATERIALS: The Active Breathing Control (ABC) device designed at William Beaumont Hospital, Michigan was used to quantify the potential benefit of radiation delivery during DIBH for five left-sided breast cancer patients. This device initiates a breath hold at a predefined, reproducible lung volume. For each patient, two CT scans were acquired with and without breath hold, and virtual simulation was performed for regular tangent and wide-tangent techniques. The resulting dose-volume histograms were calculated, and the volume of heart irradiated to 25 Gy or more was assessed. RESULTS: The influence of ABC on irradiated heart volumes varied considerably among the five patients. Three patients with substantial cardiac volume in the treatment field during normal respiration showed a significant dose-volume histogram reduction when deep inspiration was applied, with decreases in the heart volume receiving 25 Gy of more than 40 cc observed. For one patient, deep inspiration reduced irradiated cardiac volumes only with the wide-tangent technique, while one patient showed no substantial irradiated volume decrease. CONCLUSION: A DIBH technique during tangential breast irradiation has the potential to significantly decrease irradiated cardiac volume for suitably selected patients. The magnitude of the impact of the breath hold application depends on patient anatomy, lung capacity, and pulmonary function.     

Introduction of moderate deep inspiration breath hold for radiation therapy of left breast: Initial experience of a regional cancer center

PurposePractical aspects of introducing moderate deep inspiration breath hold (mDIBH) for treatment of left breast cancer in a regional cancer program in terms of workflow and treatment delivery requirements are described. Differences in heart and lung doses between free breathing (FB) and mDIBH plans are presented as well as heart position reproducibility and resulting dosimetric impact using cone beam computed tomography (CBCT).Methods and materialsA mDIBH process was established. Therapists observed duration and quantity of breath holds required for setup, imaging, and beam delivery during treatment. Treatment plans were generated on the FB and mDIBH CT datasets allowing comparison of heart and lung dose–volume data for 50 patients. Five consecutive CBCT images were used to measure the distance between the heart and chest wall for 5 patients. Estimates of dose to the translated heart were then made with the treatment planning system.ResultsWhen compared with FB delivery, mDIBH treatment time for tangents and boosts increased by 5 minutes, while 3- or 4-field techniques increased by 10 minutes. Differences in heart dose D10 cc, mean, V30 and V10 were statistically significant between the FB and mDIBH tangents and 3- or 4-field treatment plans. Statistically significant differences in V20, V10, V5, and mean lung doses were observed for 3- and 4-field FB and mDIBH plans. Differences between lung V5 dose metrics for FB and mDIBH 2-field plans were statistically significant. Interfraction mean translations in heart position coronally ranged from − 6.2 to 2.6 mm and resulted in non-negligible increases in the heart dose.ConclusionsModerate deep inspiration breath hold has been successfully implemented in our regional cancer center for treatment of left breast cancer and is now a standard practice. This change in practice from FB to mDIBH treatment has not impacted our ability to meet provincial guidelines for patient throughput.     

Patient-Specific Heart Constraint: A Tool for Optimization and Evaluation of Mean Heart Dose in Breast Cancer Patients

PurposeOur institution introduced a patient-specific heart constraint (PSHC) and a mean heart dose (MHD) constraint of 4 Gy for all patients receiving breast radiation therapy (RT) with a simultaneous boost (SIB). This was introduced as a method to calculate the predicted MHD before optimizing IMRT fields. We sought to determine whether the introduction of a PSHC reduced MHD, while maintaining optimally dosed treatment plans.Material/MethodsPatients were retrospectively divided into 2 groups, pre- and postintroduction of the PSHC. The breast and SIB Planning Target Volumes (PTVs) were prescribed to 50 Gy and 57 Gy, respectively, in 25 fractions. Plans were generated using a hybrid IMRT technique, 30 Gy using an open tangential field arrangement, and 27 Gy using IMRT fields. The PSHC was calculated using MHD of open tangential field × 2. A paired t test compared PTV coverage and heart doses between cohorts (P < .05 significant).ResultsA total of 264 patients were included (138 pre-PSHC and 126 post-PSHC) with 137 right-sided and 127 left-sided treatments. MHD was significantly reduced across both right-sided (–0.4 Gy, P < .0001) and left-sided (–1.2 Gy, P < .0001) treatments overall. Left-sided treatments were further examined between free breathing and deep inspiration breath-hold (DIBH). DIBH showed reduction in MHD, although it was not significant (–0.46 Gy, P = .34). Heart V5 Gy showed reduction in right-sided (–1%, P = .002) and left-sided (–9.2%, P < .0001) treatments overall. Left-sided free breathing showed significant reduction (–8.8%, P < .0001), and DIBH also showed significant reduction (–5.1%, P = .0034). Tumor bed doses remained above the 54.15 Gy (95% of 57 Gy) threshold for all plans.ConclusionIntroduction of a PSHC can reduce MHD and V5 Gy for patients receiving whole breast RT with SIB while maintaining optimally dosed plans, with the greatest benefit shown for left-sided, free-breathing treatments.     

Can we predict the cardiac benefit of deep inspiration breath hold for left breast and regional nodal irradiation?

PurposeDeep inspiration breath hold (DIBH) is used to decrease the dose of radiotherapy delivered to the heart. There is a need to define criteria to select patients with the potential to derive a real clinical benefit from DIBH treatment. Our study's main goal was to investigate whether two CT-scan cardiac anatomical parameters, cardiac contact distance in the parasagittal plane (CCDps) and lateral heart-to-chest distance (HCD), were predictive of unmet dosimetric cardiac constraints for left breast and regional nodal irradiation (RNI).Materials and methodsThis retrospective single-institution dosimetric study included 62 planning CT scans of women with left-sided breast cancer (BC) from 2016 to 2021. Two independent radiation oncologists measured HCD and CCDps twice to assess inter- and intra-observer reproducibility. Dosimetric constraints to be respected were defined, and dosimetric parameters of interest were collected for each patient.ResultsMean heart dose was 7.9 Gy. Inter-rater reproducibility between the two readers was considered excellent. The mean heart dose constraint < 8 Gy was not achieved in 25 patients (40%) and was achieved in 37 patients (60%). There was a significant correlation between mean heart dose and HCD (r_s = –0.25, P = 0.050) and between mean heart dose and CCDps (r_s = 0.25, P = 0.047). The correlation between HCD and CCDps and unmet cardiac dosimetric constraints was not statistically significant.ConclusionOur dosimetric analysis did not find that the cardiac anatomical parameters HCD and CCDps were predictive of unmet dosimetric cardiac constraints, nor that they were good predictors for cardiac exposure in left-sided BC radiotherapy comprising RNI.     

Dosimetric and clinical advantages of deep inspiration breath-hold (DIBH) during radiotherapy of breast cancer

Background

To investigate the potential dosimetric and clinical benefits of Deep Inspiration Breath-Hold (DIBH) technique during radiotherapy of breast cancer compared with Free Breathing (FB).

Methods

Eight left-sided breast cancer patients underwent a supervised breath hold during treatment. For each patient, two CT scans were acquired with and without breath hold, and virtual simulation was performed for conventional tangential fields, utilizing 6 or 15 MV photon fields. The resulting dose–volume histograms were calculated, and the volumes of heart/lung irradiated to given doses were assessed. The left anterior descending coronary artery (LAD) mean and maximum doses were calculated, together with tumour control probability (TCP) and normal tissue complication probabilities (NTCP) for lung and heart.

Results

For all patients a reduction of at least 16% in lung mean dose and at least 20% in irradiated pulmonary volumes was observed when DIBH was applied. Heart and LAD maximum doses were decreased by more than 78% with DIBH. The NTCP values for pneumonitis and long term cardiac mortality were also reduced by about 11% with DIBH. The NTCP values for pericarditis were zero for both DIBH and FB.

Conclusion

Delivering radiation in DIBH conditions the dose to the surrounding normal structures could be reduced, in particular heart, LAD and lung, due to increased distance between target and heart, and to reduced lung density.

     

Deep inspiration breath hold technique reduces heart dose from radiotherapy for left-sided breast cancer

Introduction: Adjuvant left breast radiotherapy (ALBR) for breast cancer can result in significant radiation dose to the heart. Current evidence suggests a dose–response relationship between the risk of cardiac morbidity and radiation dose to cardiac volumes. This study explores the potential benefit of utilising a deep inspiration breath hold (DIBH) technique to reduce cardiac doses. Methods: Thirty patients with left‐sided breast cancer underwent CT‐simulation scans in free breathing (FB) and DIBH. Treatment plans were generated using a hybrid intensity‐modulated radiation therapy technique with simultaneous integrated boost. A dosimetric comparison was made between the two techniques for the heart, left anterior descending coronary artery (LAD), left lung and contralateral breast. Results: Compared with FB, DIBH resulted in a significant reduction in heart V30 (7.1 vs. 2.4%, P < 0.0001), mean heart dose (6.9 vs. 3.9 Gy, P < 0.001), maximum LAD planning risk volume (PRV) dose, (51.6 vs. 45.6 Gy, P = 0.0032) and the mean LAD PRV dose (31.7 vs. 21.9 Gy, P < 0.001). No significant difference was noted for lung V20, mean lung dose or mean dose to the contralateral breast. The DIBH plans demonstrated significantly larger total lung volumes (1126 vs. 2051 cc, P < 0.0001), smaller maximum heart depth (2.08 vs. 1.17 cm, P < 0.0001) and irradiated heart volume (36.9 vs. 12.1 cc, P < 0.0001). Conclusions: DIBH resulted in a significant reduction in radiation dose to the heart and LAD compared with an FB technique for ALBR. Ongoing research is required to determine optimal cardiac dose constraints and methods of predicting which patients will derive the most benefit from a DIBH technique.     

Initial clinical experience with moderate deep-inspiration breath hold using an active breathing control device in the treatment of patients with left-sided breast cancer using external beam radiation therapy

INTRODUCTION: We present our initial clinical experience using moderate deep-inspiration breath hold (mDIBH) with an active breathing control (ABC) device to reduce heart dose in the treatment of patients with early-stage, left-sided breast cancer using external beam radiation therapy (EBRT) limited to the whole breast. METHODS AND MATERIALS: Between February and August 2002, 5 patients with Stages I/II left-sided breast cancer received EBRT limited to the whole breast using an ABC device. After standard virtual simulation, patients with >2% of the heart receiving >30 Gy in free breathing were selected. All patients underwent a training session with the ABC apparatus to determine their ability to comfortably maintain mDIBH at 75% of the maximum inspiration capacity. Three patients received 45 Gy to the whole breast in 25 fractions, and 2 patients received 50.4 Gy in 28 fractions. For each of the medial and lateral tangential beams, radiation was delivered during 2 or 3 breath hold durations that ranged from 18 to 26 s. "Step-and-shoot" intensity modulation was employed to achieve uniform dose distribution. Open beam segments were purposely delivered over 2 breath hold sessions and captured on electronic portal images to allow intra- and interfraction setup error analysis. All electronic portal images of the tangential beams were analyzed off-line using an in-house treatment verification tool to assess the anteroposterior, craniocaudal, and rotational uncertainties. Corrections were applied if necessary. RESULTS: A comparison of treatment plans performed on breath-hold and free-breathing CTs showed that ABC treatments achieved a mean absolute reduction of 3.6% in heart volume receiving 30 Gy (heart V(30)) and 1.5% in the heart normal tissue complication probability. A total of 134 ABC treatment sessions were performed in the 5 patients. The average number of breath holds required per beam direction was 2.5 (4-6 per treatment) with a median duration of 22 s per breath hold (range: 10-26 s). Patients tolerated mDIBH well. The median treatment time was 18.2 min (range: 13-32 min), which was progressively shortened with increasing experience. A total of 509 portal images were analyzed. Combining measurements for all patients, the interfraction setup errors (1 SD) in the lateral and craniocaudal directions and in rotation were 2.4 mm, 3.2 mm, and 1 degrees, respectively, for the medial beam and 2.3 mm, 3.1 mm, and 1 degrees, respectively, for the lateral beam. For all patients, the intrafraction setup errors were about 1 mm and always less than 2 mm (1 SD). CONCLUSION: Reduction in heart V(30) can be achieved in patients with left-sided breast cancer using mDIBH assisted with an ABC device. With increasing experience, ABC treatments were streamlined and could be performed within a 15-min treatment slot. Our results suggest that mDIBH using an ABC device may provide one of the most promising methods of improving the efficacy of EBRT in patients with left-sided breast cancer, particularly when wide tangential beams are employed.Breast cancer; Breath hold; Radiation therapy; Intensity modulated radiation therapy     

Effects of Preparatory Coaching and Home Practice for Deep Inspiration Breath Hold on Cardiac Dose for Left Breast Radiation Therapy

Aims

Deep inspiration breath hold (DIBH) reduces cardiac radiation exposure by creating cardiac–chest wall separation in breast cancer radiotherapy. DIBH requires sustaining chest wall expansion for up to 40 s and involves complex co-ordination of thoraco-abdominal muscles, which may not be intuitive to patients. We investigated the effect of in-advance preparatory DIBH coaching and home practice on cardiac doses.